A safety problem is associated with the elevating type dock boards that are widely utilized to adapt a fixed elevation dock surface to the different height loading surfaces of trucks or railroad cars, include a ramp which is mounted in a pit formed in the dock area for vertical swinging movement. Such a ramp comprises a rigid frame having an upper surface or transport plate across which persons and transport vehicles such as forklifts may be moved for carrying of goods. To accommodate the dock boards to the various height of vehicles with comparison to the dock, this ramp is pivoted for swinging movement in a vertical plane to various inclined positions. It is necessary that the ramp be capable of being pivoted to a relatively downwardly inclined or depressed position with respect to the dock and the ramp as well as swing to a substantially elevated position with respect to a coplanar position relative to the dock surface. The problem with the basic constructional feature of a supporting frame for the ramp which is pivoted into and out of the pit area, is that this frame structure can result in injury to persons who may be standing adjacent to the dock and inadvertently place their feet into the space through which the structural frame members of the ramp pivot during the indicated movements.
Attempts have been made to provide an effective toe guard which can be positioned in association with the ramp of the dock board and provide the necessary protection to prevent insertion of a person's foot into the operating area of the ramp. An example, of such a prior device, is that illustrated in Pat. No. 3,886,615 issued to Robert D. Metro on June 3, 1975. That patent discloses a dock board of the generally utilized type and includes the provision of vertically disposed plates which perform a function in protecting a person's foot by closing at least a portion of the space which would otherwise be open at each side of the ramp when the ramp is in a relatively upwardly pivoted position with respect to the surface of the adjoining areas of the dock. The toe guard disclosed in that patent comprises a single plate which is pivoted for vertical swinging movement about the same axis as the ramp pivot axis and, when the ramp is closed or moved to a depressed position, the toe guard plate is merely supported on the adjacent edge portions of the dock. This permits the ramp to be able to move through its entire vertical pivoting extent as intended for its designed operation.
As indicated in that patent, the problem in obtaining the optimum and best protection for persons is the substantial extent of vertical swinging of a dock board in comparison to the vertical dimensions of the pit in which such a dock board is mounted. Generally the pit area is relatively shallow as most dock boards of this type are designed and fabricated to have a minimum vertical extent for reasons of economy and to facilitate installation in existing dock areas. Consequently, a protective toe guard plate is limited to a fixed or maximum vertical dimension which is determined by the available storage height that exists in the pit area for the dock board. Therefore, since most dock boards are capable of a vertical swinging movement at their outer ends that is essentially greater than the vertical height of the pit, a single protective toe guard plate is incapable of providing protection when the ramp is swung to its uppermost position.